package org.bouncycastle.crypto.modes;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.InvalidCipherTextException;

/**
 * A block cipher mode that includes authenticated encryption with a streaming
 * mode and optional associated data.
 * 
 * @see org.bouncycastle.crypto.params.AEADParameters
 */
public interface AEADBlockCipher {
    /**
     * initialise the underlying cipher. Parameter can either be an
     * AEADParameters or a ParametersWithIV object.
     * 
     * @param forEncryption
     *            true if we are setting up for encryption, false otherwise.
     * @param params
     *            the necessary parameters for the underlying cipher to be
     *            initialised.
     * @exception IllegalArgumentException
     *                if the params argument is inappropriate.
     */
    public void init(boolean forEncryption, CipherParameters params)
            throws IllegalArgumentException;

    /**
     * Return the name of the algorithm.
     * 
     * @return the algorithm name.
     */
    public String getAlgorithmName();

    /**
     * return the cipher this object wraps.
     * 
     * @return the cipher this object wraps.
     */
    public BlockCipher getUnderlyingCipher();

    /**
     * encrypt/decrypt a single byte.
     * 
     * @param in
     *            the byte to be processed.
     * @param out
     *            the output buffer the processed byte goes into.
     * @param outOff
     *            the offset into the output byte array the processed data
     *            starts at.
     * @return the number of bytes written to out.
     * @exception DataLengthException
     *                if the output buffer is too small.
     */
    public int processByte(byte in, byte[] out, int outOff)
            throws DataLengthException;

    /**
     * process a block of bytes from in putting the result into out.
     * 
     * @param in
     *            the input byte array.
     * @param inOff
     *            the offset into the in array where the data to be processed
     *            starts.
     * @param len
     *            the number of bytes to be processed.
     * @param out
     *            the output buffer the processed bytes go into.
     * @param outOff
     *            the offset into the output byte array the processed data
     *            starts at.
     * @return the number of bytes written to out.
     * @exception DataLengthException
     *                if the output buffer is too small.
     */
    public int processBytes(byte[] in, int inOff, int len, byte[] out,
            int outOff) throws DataLengthException;

    /**
     * Finish the operation either appending or verifying the MAC at the end of
     * the data.
     * 
     * @param out
     *            space for any resulting output data.
     * @param outOff
     *            offset into out to start copying the data at.
     * @return number of bytes written into out.
     * @throws IllegalStateException
     *             if the cipher is in an inappropriate state.
     * @throws org.bouncycastle.crypto.InvalidCipherTextException
     *             if the MAC fails to match.
     */
    public int doFinal(byte[] out, int outOff) throws IllegalStateException,
            InvalidCipherTextException;

    /**
     * Return the value of the MAC associated with the last stream processed.
     * 
     * @return MAC for plaintext data.
     */
    public byte[] getMac();

    /**
     * return the size of the output buffer required for a processBytes an input
     * of len bytes.
     * 
     * @param len
     *            the length of the input.
     * @return the space required to accommodate a call to processBytes with len
     *         bytes of input.
     */
    public int getUpdateOutputSize(int len);

    /**
     * return the size of the output buffer required for a processBytes plus a
     * doFinal with an input of len bytes.
     * 
     * @param len
     *            the length of the input.
     * @return the space required to accommodate a call to processBytes and
     *         doFinal with len bytes of input.
     */
    public int getOutputSize(int len);

    /**
     * Reset the cipher. After resetting the cipher is in the same state as it
     * was after the last init (if there was one).
     */
    public void reset();
}
